The objective of this proposal is to study exchange reactions of organomercurials with mercaptans and disulfides. The relative rate of alkyl and ligand exchange for a series of compounds that have a Hg-S bond will be examined. The mode of reaction and the rate of cleavage of the S-S linkage with organic and inorganic mercuric salts will be examined. We also propose to ascertain which substrates will undergo C-Hg bond cleavage. These data will be related to the existing ecological problems associated with mercury contamination of the environment.